DOs and DONTs for small ISP

Mon Jun 3 13:56:46 UTC 2019

On Mon, 3 Jun 2019, Mehmet Akcin wrote:

> hi there,
> 
> I know there are folks from lots of small ISPs here and I wanted to check-in on asking few advice points as I am involved building an ISP from green-field.
> 
> Usually, it's pretty straight forward to cover high-level important things, filters, routing policies, etc.but we all know the devil is in the details. 
> 
> I am putting together a public DOs and DONTs blog post and would love to hear from those who have built ISPs and have recommendations from Billing to Interconnection, Routing policy to Out of
> the band  & console setup, Software recommendations, etc. Bottom line is that I would like to publish a checklist with these recommendations which I hope will be useful for all. 
> 
> thanks in advance for your help and recommendation.

Probably the #1 thing I've seen messed up is BGP config.

1) Nail up your routes using network statements and static null
    routes.  Don't rely on redistribute connected to advertise what's
    configured on an ethernet interface.  You probably shouldn't be using
    redistribute at all unless you "know what you're doing" with it.

2) Don't advertise your v4 IP space as a collection of /24s if you have a
    larger aggregate block, unless you have good reason to do so...and if
    you do, you should probably still advertise the aggregate unless
    there's a good reason not to.

3) Don't advertise one transit provider's routes to another.  Each should
    be filtering your routes, but you never know.  Come up with, and use
    BGP communities to control route propagation.  As you grow, it sucks
    having to update prefix-list filters in multiple places every time
    something changes...like a new customer with their own IPs.

----------------------------------------------------------------------
  Jon Lewis, MCP :)           |  I route
                              |  therefore you are
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